最新刊期
卷 31 ， 期 4 ， 2012
- 摘要：The trace impurities of gutter oils were investigated by gas chromatography-mass spectrometry（GC-MS)with solid phase microextraction（SPME).By comparison of the trace endogenous substances of various pure vegetable oil and the exogenous impurities of the gutter oils from different areas,together with the analysis of the source of exogenous impurities,the characteristic components of the gutter oils from Guangzhou,Guizhou,Shenzhen and Beijing were acquired,which can be used as indicated components for the distinguishment of gutter oils.With high sensitivity and characteristic,this method was recruited in the blind samples evaluation organized by the Ministry of Public Health and the accuracy on positive samples was as high as 95.5%.关键词：Solid-phase microextraction（SPME);gas chromatography-mass spectrometry（GC-MS);gutter oils;characteristic substance;source analysis;identification;determination
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发布时间： - 摘要：Eight kinds of reheated oils（genetically modified soybean oil，non genetically modified soybean oil，sunflower oil，peanut oil，corn oil，safflower oil，cooking oil，olive oil） were identified by fourier transform infrared spectroscopy（FT-IR）.Unsaturated degree of unsaturated fatty acids（e.g，linoleic acid and linolenic acid） in cooking oil decreased and saturated fatty acids（e.g.palmitic acid and stearic acid） increased under the condition of high temperature reheating，while the cis fatty acids were also changed to be trans fatty acids.The absorption of the peak at 3 009，988，966 cm-1 were selected as characteristic absorption peak of the alkene and trans structure by second order derivative spectrophotometry.This method，with the advantages of simplicity，small dosage and rapidness for quality analysis of reheated oil in market screening，could be used as the theoretical evidence for determination of waste oil.关键词：FT-IR;attenuated total reflection（ATR）;cooking oil;second order derivative spectrophotometry;repeatedly heated to high temperatures;hogwash oil
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发布时间： - 摘要：A new method was established for the determination of sodium dodecylbenzene suifnate（SDBS） in hogwash fat by ultraviolet-visible spectrophotometry.SDBS was extracted with distilled water,and reextracted with trichloromethane.The SDBS was determined after the coloration by methylene blue in the hogwash fat.The experimental factors such as extraction temperature and time were investigated.The optimal conditions were as follows:extraction time:2 h,extraction temperature:50 ℃ and detection wavelength:645 nm.Under the optimal conditions,the detection limit of SDBS was 0.1 μg/kg.The recoveries of SDBS in oil sample at spiked levels of 1.0,5.0,10.0,20.0 μg/kg were in the range of 94%-96% with RSDs less than 5%.The results of 5 groups of actual samples showed that the average of SDBS residues in hogwash fat was 19.19 μg/kg while the SDBS content in high-quality edible oil was 0.35 μg/kg.The testing results of actual samples showed that the SDBS contents in the hogwash fat were of big differences,but the contents were overall higher than those of the edible oil.The method could be used in the discrimination of hogwash fat.关键词：hogwash fat;edible oil;ultraviolet-visible spectrophotometry;sodium dodecylbenzene suifnate（SDBS）
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发布时间： - 摘要：Mycotoxins are toxic secondary metabolites produced by filamentous fungi that grow on grain commodities.They have been widely recognized as the main undesirable substances in grain.A method using liquid chromatography-time of flight mass spectrometry（LC-TOF MS） was developed for simultaneous determination of 13 mycotoxins derived from the fungal genera of Fusarium,Aspergillus and Penicillum in wheat and maize.The samples were extracted with acetonitrile-water-acetic acid （84∶15∶1）,and cleaned up on the Mycosep 226 multifuctional cartridge and the strong anion exchange cartridge.The purified extracts were analysed by LC-TOF MS under the mode of positive electrospray ionization,the mycotoxins were identified by the retention time and the mass accuracy of［M+H］+ or ［M+NH4］+ and quantified in exact mass chromatograms with a mass window width of 10 ppm.The results indicated that 13 mycotoxins had good linear relationships in the certain concentration ranges with their correlation coefficients more than 0.99 and the accurate mass errors less than 5 ppm.The average recoveries of 13 mycotoxins at three spiked levels ranged from 70% to 113% with relative standard deviations of 0.2%-14.5%.The method was suitable for the identification and quantification of targeted mycotoxins at trace level in grain.关键词：liquid chromatography-time of flight mass spectrometry（LC-TOF MS）;mycotoxins;grain;simultaneous determination
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发布时间： - 摘要：A cobalt hexacyanoferrate（CoHCF） film was successfully electrodeposited on functionalized multi-wall carbon nanotubes（MWNTs） modified glassy carbon electrodes by scanning the potential between 0 V and 1.1 V at a scan rate of 100 mV/s for 20 consecutive scans in an aqueous electrolyte of 0.5 mol/L KCl, 1 mmol/L CoCl2 and 0.9 mmol/L K3Fe(CN)6.The modified electrodes （MWNTs-CoHCF/GCE） were characterized by scanning electron microscope and cyclic voltammetric methods.It was found that the CoHCF film was covered with the MWNTs.The MWNTs-CoHCF/GCE presented a nanoporous structure with an excellent electrochemical stability,which showed a favorable electron transfer kinetics.The cyclic voltammetric experiment showed that the MWNTs-CoHCF/GCE had a favorable electrochemical activity for the oxidation of vitamin B2 （VB2）,and the peak current was linear over VB2 concentration in the range of 1.2×10-7-2.6×10-7 mol/L with a detection limit（S/N=3） of 8.9×10-8 mol/L.关键词：carbon nanotubes;cobalt hexacyanoferrate;vitamin B2;nanoporous film;biosensor;electrodeposition
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发布时间： - 摘要：An immunochromatographic assay（ICA） method for the detection of chromium ions（Cr3+） was developed.Colloidal gold particles coated with affinity purified monoclonal anti isothiocyanobenzyl-EDTA（iEDAT）-chelated Cr3+ antibodies were used as detection reagent，and the strip was prepared by arraying the synthetic Cr3+-EDTA-BSA and goat anti-mouse immunoglobulins on cellulose nitrate film to form the test（T） band and control（C） band.The prepared strip was used to detect Cr6+ when it was reduced to Cr3+ by NaHSO3.The visual lowest detection limities（LDL） of the test strip was as low as 50 μg/L.The test trips showed negligible cross-reactivities with 10 heavy metals except for 1 000 μg/L Fe3+-EDTA.The determination result of water samples containing chromium standard by the prepared strip was consistent with that by ICP.Because of its sensitivity，specifity，low cost and fast result（within 5 min），the test strip is especially suitable for the on-site large scale screening on Cr-contained water samples and many other applications.关键词：chromium ions;colloidal gold;immunochromatography assay;water sample;monoclonal antibody
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发布时间： - 摘要：A highly sensitive precolumn high performance liquid chromatographic（HPLC） method for the simultaneous determination of free hydroxyproline（Hyp） and proline（Pro） in human urine was developed.Effects of reaction temperature,pH value,time,concentration of labeling reagent,composition of moblie phase,concentration and pH value of buffer,and column temperature were investigated in detail.Under the optimal conditions,the calibration curves showed good linear relationship in the concentration ranges of 5-100 μmol/L for hydroxyproline and 5-250 μmol/L for proline.The correlation coefficients were 0.999 4 for hydroxyproline and 0.999 5 for proline.The detection limits（S/N=3） for hydroxyproline and proline were 0.50 nmol/L and 0.20 nmol/L,respectively.The recoveries（n=5） for hydroxyproline and proline were in the ranges of 95%-99% and 96%-102% with RSDs of 2.1%-4.3%and 2.0%-4.8%,respectively.This method can be used for the qualitative analysis of free hydroxyproline and proline in human urine sample.关键词：derivation;hydroxyproline;proline;4-methoxybenzenesulfonyl chlorine;high performance liquid chromatography;human urine
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发布时间： - 摘要：Based on the polyaniline nano fiber（PANI-NF） nanometer gold composite film（AuNPs） constructing electrode interface and then modified by transferrin，HeLa cells can be captured on the modified electrode due to the specific identification function by transferrin and transferrin receptor，resulting in the variation of electrochemical impedance values.The effects of drug（curcumin meat） on HeLa cells were investigated by ectrochemical impedance spectroscopy.The results showed that with the increase of drug concentration and prolongation of function time，electrochemical impedance values were decreased，indicating that the inhibition effects of drug（curcumin） on HeLa cells were enhanced.A quantitative relation between the change rate of electrochemical impedance values，drug concentration and treating time was observed.The results of electrochemical experiment are in accordance with that of the MTT method and inverted microscope.Based on this，a new method for testing the inhibition rate of drug on cells was established.The method is simple，high sensitivity and low cost.关键词：AuNPs/PANI-NF composite film;electrochemical cells sensor;curcumin;cell apoptosis
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发布时间： - 摘要：A molecularly imprinted polymer（MIP）,which has a specific selectivity to dopamine，was synthesized using dopamine as template and 3-aminopropyltriethoxysilane modified mesoporous silica as carrier.The MIP was used to fabricate a sensor for the determination of dopamine,which response to dopamine（DA） was evaluated by cyclic voltammetry.Under the optimized conditions，the sensor displayed good linearities in the ranges of 1.0×10-7-2.0×10-6 mol/L and 2.0×10-6-1.0×10-4 mol/L with a lower detection limit of 1.3×10-9 mol/L.The correlation coefficients were 0.992 5 and 0.996 9，respectively.The studied imprinted sensor exhibited high sensitivity and selectivity，and was successfully applied in the determination of dopamine in human blood plasma.关键词：molecularly imprinted polymer;mesoporous silica;electrochemical sensor;dopamine
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发布时间： - 摘要：A new reagentless amperometric immunosensor for the detection of α-fetoprotein antibody （anti-AFP） molecule based on Nafion，Fe3O4@ thionine and gold nanoparticles was fabricated.Firstly，Fe3O4@ thionine nanoparticles were prepared by magnetic separation method.Nafion、Fe3O4@ thionine nanoparticles were modified on glassy carbon electrode layer by layer through electrostatic adsorption,then the NH2 of thionine molecules was used to adsorbed the gold nanoparticles.Finally，with function of gold nanoparticles adsorbing AFP antibody，a reagentless amperometric AFP immunosensor with high stability and sensitivity was prepared successfully. Transmission electron microscopy and cyclic voltammetry were used to characterize the composite nanoparticles and the property of the immunosensor.Under the optimal conditions，the immunosensor had a good current response to AFP with a detection range of 0.05-20 μg/L and a detection limit of 0.03 μg/L.关键词：Fe3O4 nanoparticles;thionine;gold nanoparticle;α fetoprotein;immunosensor
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发布时间： - 摘要：A simple DESI source was built.The experimental conditions were optimized and used in the analysis of a few common peptides and proteins.The results indicated that peptides and small proteins（＜20 kDa） can be easily ionized and well defined mass spectra were generated.However，BSA （66.4 kDa） generated a poorly defined mass spectrum，which implies that there might be a molecular weight upper limit for the current design of the DESI source.The comparison between DESI and ESI mass spectra reveals that solvent evaporation can significantly affect the charge distribution and peak width，maybe due to the fact that ESI is softer than DESI.Self-assembled monolayer（SAM） on gold surface has a higher insulation than that on bare gold surface，so SAM surface can assist the survival of ions，indicating that the electron transfer（electrical neutralization） from the surface is an important factor in the ionization process of DESI.This study will be helpful for the selections of experimental conditions and sample surfaces for DESI-MS，and enhance the understanding of the ionization mechanism of DESI.关键词：desorption electrospray ionization（DESI）;ESI;mechanism;protein analysis;self-assembled monolayer
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发布时间： - 摘要：A new method，based on the composite application of the iterative algorithm，the partial least squares（PLS） and the ultraviolet spectrophotometry，was presented for the simultaneous determination of three tolualdehyde isomers among the six components prepared by indirect electrosynthesis with the xylene.The PLS was enchased to the iterative algorithm to obtain the approximation through the interactive calculations，which could improve the spectral identification ability of the products.The proposed method was applied in the simultaneous determination of three tolualdehyde isomers in four simulating samples with satisfactory results.The mean recoveries of o-tolualdehyde，m-tolualdehyde and p-tolualdehyde were 101%，100% and 101%，respectively，and root mean square errors of prediction（RMSEP） were 0.214，0.148 and 0.057，respectively.The practical application to five group electrosynthesis tolualdehyde products showed that the average recoveries were 106%，92% and 100% for o-tolualdehyde，m-tolualdehyde and p-tolualdehyde，respectively，and the relative error was less than 19.7%.The results were compared with those obtained from the HPLC method with no significant difference.关键词：tolualdehyde;isomers;partial least square;ultraviolet spectrum;simultaneous determination
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发布时间： - 摘要：A high performance liquid chromatography-electrospray ionization tandem mass spectrometric（HPLC-ESI MS/MS） method was developed for the determination of seven plant growth regulator residues，including parachlorophenoxyacetic acid，gibberellic acid（GA3），2,4-dichlorophenoxyacetic acid，α-naphthaleneacetic acid，indolebutyric acid，6-benzylaminopurine and forchlorfenuron in fruits and vegetables. Plant growth regulators were extracted twice from samples with methanol and the extracts were cleaned up on a Waters C18 solid phase extraction column（SPE，0.5 g，3 mL）.The qualitation of the analytes was achieved under selective reaction monitoring（SRM） mode,and the quantification of the analytes was carried out by the external standard method .The chromatography separation was performed on a Hypersil GOLD aQ（150 mm×2.1 mm，3 μm） column by gradient elution with methanol and water as mobile phase.Under the optimal conditions，good linearities were obtained for seven plant growth regulators with their correlation coefficients no less than 0993 5.The average recoveries of seven plant regulators in fruits and vegetables samples at three spiked levels ranged from 79% to 97%，with relative standard deviations（RSDs） no more than 7.6%.The limits of detection（LODs） were in the range of 0.40-200 μg/kg.The result showed that the method was simple and sensitive，and was applicable for the detection of plant growth regulators.关键词：high performance liquid chromatography-tandem mass spectrometry（HPLC-MS/MS）;plant growth regulator;fruits and vegetables;residue
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发布时间： - 摘要：An analytical method was developed for the simultaneous determination of 11 banned azo=dyes （Sudan red Ⅰ，Sudan red Ⅱ，Sudan red Ⅲ，Sudan red Ⅳ，Sudan red 7B，Sudan red G，Sudan yellow，Sudan orange G，Sudan blue Ⅱ，toluidine red，para red） and rhodamine B in seasoning oil based on gel permeation chromatography followed by ultra performance liquid chromatography-tandem mass spectrometry（UPLC-MS/MS）.The seasoning oil samples were extracted with cyclohexane-ethyl acetate（1∶1），and then purified by gel permeation chromatography to remove the high molecular weight of interferences（e.g.fat，oil and natural pigments）.Twelve target compounds were separated on an ACQUITY UPLC- BEH C18 column with 0.1% formic acid and acetonitrile as mobile phase by gradient elution，and detected by MS/MS under positive mode with multiple reaction monitoring（MRM）.Good linearities for 12 dyes were achieved over the range of 1-50 μg/L.The quantitation limits of 12 dyes in seasoning oil samples were in the range of 0.2-2.5 μg/kg.The mean recoveries at three spiked level（5，20，40 μg/L） ranged from 54% to 125%， with relative standard deviations（RSDs） of 2.5%-17.2%.The method was used to analyze 35 seasoning oil samples taken randomly from the local market，and rhodamine B was found in 2 of the samples.The established method could be applied in the simultaneous extraction and purification of 11 azo-dyes and rhodamine B in seasoning oil matrix，and is suitable for the routine detection of illegally additive dyes in seasoning oil due to its simplicity and high sensitivity.关键词：gel permeation chromatography（GPC）;ultra performance liquid chromatography-tandem mass spectrometry（UPLC-MS/MS）;azo-dyes;rhodamine B;seasoning oil;determination
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发布时间： - 摘要：With the employment of solid phase extraction and high performance liquid chromatography tandem mass spectrometry（HPLC-MS/MS），a method was developed for the determination of 21 antibiotics，including twelve sulfonamides，four quinolones，three tetracyclines，roxithromycin and trimethoprim，in hospital wastewater.In the acid condition，target compounds were enriched with Oasis HLB column and purified with 10% menthol.The analytes were eluted with methanol，and subsequently quantified by HPLC-MS/MS under multi-reaction monitoring（MRM） mode.Under the optimal conditions，the calibration curves of all 21 targets were linear in the range of 1.0-500 μg/L with correlation coefficients more than 0.99.The spiked recoveries at two levels of 0.05 μg/L and 1.0 μg/L were in the ranges of 71%-105% and 76%-111%，respectively,with relative standard deviations（RSDs） less than 15%.The method detection limits varied between 0.005 μg/L and 0.022 μg/L.The average recoveries of 21 antibiotics in the hospital wastewater samples ranged from 71% to 135%,with RSDs less than 25%.This method was simple，rapid and accurate，and could meet the requirements for monitoring on antibiotics residues in hospital wastewater.关键词：determination;antibiotics;hospital wastewater;solid phase extraction;HPLC-MS/MS
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发布时间： - 摘要：An anodic stripping voltammetric method for the determination of arsenite using Au-Pd bimetallic nanoparticles（Au-Pd NPs） modified glassy carbon electrode（Au-Pd/GCE） was developed.The structural information and electrochemical activities of the synthesized Au-Pd nanoparticles were investigated with UV-Vis spectroscopy，high resolution transmission electron microscopy（HRTEM） and cyclic voltammetric（CV） method.The determination of arsenic was conducted by square wave voltammetric（SWV） method.Effects of deposition potential and SWV parameters (such as frequency，increment and amplitude) on the current intensity of arsenite were investigated.The results showed that Au-Pd bimetallic nanoparticles presented a core-shell structure in shape and the modified electrode exhibited the characteristic peaks of both Au and Pd.A sensitive anodic stripping peak of arsenite appeared at about 0.30 V，and the peak current was linear with concentration of arsenite in the range of 0.5-20 μg/L with a limit of detection（LOD） of 0.15 μg/L，which is far below the maximum guideline value（10 μg/L） set by World Health Organization（WHO）.The modified electrode exhibited a good repeatability toward the consecutive determination of arsenite.The interference experiments also showed that except for Cu（Ⅱ），the existance of Pb（Ⅱ），Cd（Ⅱ） and Zn（Ⅱ） would not affect the detection of As（Ⅲ）.关键词：Au-Pd bimetallic nanoparticles;glassy carbon electrode;stripping voltammetry;arsenite
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- 2
发布时间： - 摘要：A poly（methylene blue）/graphene modified glassy carbon electrode（PMB/GH/GCE） was fabricated by electropolymerizing methylene blue on the surface of glassy carbon electrode modified with graphene.The electrochemical behaviors of dopamine（DA） and ascorbic acid（AA） at the prepared electrodes were investigated using cyclic voltammetry（CV） and differential pulse votammetric（DPV） methods.In pH 6.9 phosphate buffer solution（PBS）,the anodic peak potentials of DA and AA were 0.208 V and -0.108 V，respectively.In comparison with poly（methylene blue） modified glassy carbon electrode（PMB/GCE） and graphene modified glassy carbon electrode（GH/GCE）,the composite modified electrode（PMB/GH/GCE） had superior electrocatalytic activity toward the oxidation of DA and AA,with a peak to peak separation up to 316 mV.Studies showed that MB was firmly non-covalent modification of graphene by electropolymerizing method,and created synergistic effect which could improved sensitivity and molecular recognition ability of the modified electrodes and enabled the sensitive and selective detection of DA in the presence of large number of AA.A DPV technique for measurement for DA over the range of 1.00×10-7-5.00×10-3 mol/L was developed in the presence of 1.00×10-3 mol/L AA,with detection limit of 1.00×10-8 mol/L.The modified electrode was applied in the determination of dopamine hydrochloride injection solution with satisfactory result.关键词：poly（methylene blue）;graphene;modified electrode;dopamine;ascorbic acid
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发布时间： - 摘要：Effects of the variations of pH value，temperature and colloidal particles in extractant solutions on heavy metals speciations were investigated by the sequential extraction procedure（SEP） used in anoxic sediments at mariculture zone.The results showed that a slight increasement of pH values of extractant solutions lead to the decrease of concentrations of Cd and Zn in Step1 of SEP for acid soluble speciations，However，the obvious variations of pH values of extractant solutions had no significant influence on heavy metals speciations in Step2 for reducible fraction and Step3 for organic matter bound fraction（except Pb），respectively.The temperature of extractant solutions were slightly increased in Step1 and Step2 and decreased in Step3 due to the different reaction thermodynamics in extraction steps of SEP，and the variations of temperature（＜2.5 ℃） had little effects on the concentrations of heavy metals speciations.Due to adsorption，the formation of colloid in Step1，Step2 and Step4 resulted in the decrease of Cd，Zn and Cu concentrations，respectively.However，the formation of colloid was controlled by extractant in Step3.Therefore，controlling pH and colloid in extractant solutions were available to improve the stability and accuracy of extraction results when SEP was applied to evaluate heavy metals speciations in anoxic sediments.关键词：anoxic sediment;heavy metal speciation;sequential extraction;colloid;stability
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- 1
发布时间： - 摘要：An inductively coupled plasma optical emission spectrometric （ICP-OES） method was developed for the determination of metallic impurities in pharmaceutical ingredients.The samples were directly dissolved with organic mixed solvent （DMSO∶H2O=4∶1）.The conditions of instrument were optimized，and the 14 metal elements listed in EMEA guidance could be rapidly analyzed by the method.The detection limits were less than 0.30 mg/kg，and the recoveries of the 14 metal elements ranged from 90% to 115%.The data was compared with those obtained from the different treatment methods.The results showed that the method,with the advantages of simplicity，easy operation and high accuracy，was suitable for the quick determination of multi-elements in large quantities of samples.关键词：ICP-OES;dimethyl sulfoxide;metal catalysts;pharmaceutical ingredients;determination;heavy metal
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发布时间： - 摘要：A high performance liquid chromatography- tandem mass spectrometric(HPLC- MS/MS) method was developed for the determination of cefquinome residues in animal tissues,such as beef,pork,chicken,fish and loach.The sample was extracted with acetonitrile -water(4∶1) and cleaned up with Sephadex LH-20 gel column(16 mm i.d.×320 mm).The separation of cefquinome was performed on a CAPCELL PAK MG C18(100 mm ×2.0 mm,3 μm) column using a mobile phase of 0.1% formic acid- methanol by gradient elution at a flow rate of 0.2 mL/min.The electrospray was operated in the positive ionization mode and cefquinome was identified under selective reaction monitoring(SRM) mode.The ion pairs,m/z 529.1/134.2,529.1/396.1 and 529.1/125.1 were selected as the qualitative ion pairs,and m/z 529.1/134.2 was used as the quantitative ion pair.Under the optimal conditions,the calibration curve showed a good linearity in the range of 5.0-200 μg/L for cefquinome with a correlation coefficient of 0.999 1.The limit of detection(LOD,S/N≥3) for cefquinome was 1.0 μg/kg and the limit of quantitation(LOQ,S/N≥10) was 3.0 μg/kg.The recoveries of cefquinome at four spiked concentration levles of 3.0,10,50 and 100 μg/kg ranged from 75% to 105%,with relative standard deviations(RSDs,n=6) of 2.4% - 11.9%.With the advantages of high cleanup effectiveness,good reproducibility and high sensitivity,the method could meet the requirements for the determination of cefquinome residues in animal tissues.关键词：cefquinome;gel permeation chromatography;liquid chromatography tandem mass spectrometry;residue;livestock;aquatic products
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- 0
发布时间： - 摘要：A method based on high performance liquid chromatography tandem mass spectrometry（HPLC-MS/MS） with accelerated solvent extraction（ASE） was developed for the quantitative detection of perfluorooctanoic acid（PFOA） in plastic component of the household appliances.The sample was extracted with accelerated solvent extraction using methanol as extraction solvent.The extract were purified and enriched on a C18 column by solid phase extraction（SPE） column.The target compound was separated on a C18 column using methanol-water as mobile phase by gradient elution，and detected by MS with electrospray ionization（ESI） under multiple reaction monitoring(MRM) mode.The calibration curve was linear in the range of 0.5-100.0 μg/L with a correlation coefficient（r2） of 0.998 9.The recoveries for PFOA were in the range of 93%-107% with relative standard deviations of 2.9%-7.6%.The detection limit（S/N=3） was 0.5 μg/kg.The method is easy-handling，time-saving and sensitive, and is suitable for the determination of PFOA in plastic component of household appliances.关键词：high performance liquid chromatography tandem mass spectrometry（HPLC-MS/MS）;perfluorooctanoic acid（PFOA）;plastic component of household appliances;accelerated solvent extraction（ASE）
- 1870
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- 1148
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发布时间： - 摘要：A gas chromatography-triple quadrupole mass spectrometric method was developed and validated for the determination of methyl selenocysteine in middle-aged milk powder.The analytes were extracted with trichloroacetic acid and acetonitrile,and derived with ethyl chloroformate in ethanol-pyridine.Methyl selenocysteine was separated on an HP-5MS micro-column,and quantified under multiple reaction monitoring mode.The calibration curve was linear in the range of 0.005 – 1.0 mg/L,with detection limit of 0.01 mg/kg and quantitation limit of 0.05 mg/kg.The average recoveries of methyl selenocysteine from middle-aged milk matrixes at the spiked level of 0.05,0.2,0.4 mg/kg ranged from 79% to 86% with relative standard deviations of 2.8%-4.0%.The method could meet the requirement for determination of methyl selenocysteine in middle-aged milk powder.关键词：methyl selenocysteine;gas chromatography-triple quadrupole mass spectrometry;middle-aged milk powder;ethyl chloroformate
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发布时间： - 摘要：Food allergy is an abnormal response of organism to the immune system caused by foods.In recent decades,Food allergy patients has risen gradually worldwide and food allergy has become an emerging issue of food safety.It is important to find processing methods to reduce food anaphylaxis as extremely trace of the allergen can make some patients experience strong allergic reaction.In this paper,hypoallergenic processing methods of food allergen and their corresponding evaluation systems in recent years are reviewed.Enzymatic hydrolysis method,physical methods and biochemical combining physical methods are analysed,and the methods of in vitro evaluation and animal model evaluation system of food allergenicity are compared.The development direction of hypoallergenic processing methods of food allergen and their evaluation systems are also discussed.关键词：food;allergen;hypoallergenic;processing methods;in vitro evaluation;animal model;development progress
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发布时间： - 摘要：Quartz crystal microbalance（QCM） is one of the mass-sensitive detectors.It is widely used in many fields such as environmental monitoring,pharmaceutical analysis,food quality control,etc,due to its high sensitivity,fast response and low cost.The development of chiral engineering requires chiral analytical technology with simple handling,high speed and on-line operation.QCM chiral sensor represents one of the most important branches of future research.In this review,the typical experimental apparatus and the basic principle of QCM are introduced in brief,then the recent coating materials used for QCM in chiral recognition are reviewed in detail,which include cyclodextrin derivatives,molecular imprinting polymers,amino acid derivatives,etc.The prospects of this field are also put forward.关键词：quartz crystal microbalance(QCM);chiral recognition;review
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